Compressed breathing air must meet at least the requirements for Type 1 - Grade D breathing
air described in ANSI/CGA G-7.1-1989:

Oxygen content (v/v) of 19.5 - 23.5%

Hydrocarbon (condensed) content of 5 milligrams per cubic meter (mg/m3) of air or less

CO content of 10 parts per million (ppm) or less

CO2 content of 1,000 ppm or less

Lack of noticeable odor

Compressors supplying breathing air to respirators must be equipped with suitable in-line
air-purifying sorbent beds and filters that are maintained and replaced or refurbished per
manufacturer’s instructions